White Leghorn two-year old hens are entered into a two-year chemoprevention trial, wherein birds are randomized to diet control or diet containing 4-HPR, or Levonorgestrel at a dose comparable to the common contraceptive Nodette. A variety of surrogate endpoint biomarkers are used to validate each of the ovarian cancer preventive agents that are tested in the trial. The demonstration that the molecular biology of ovarian cancers in the fowl are similar to those seen in women is a critical step toward establishing the validity of the chicken model for testing chemopreventive agents.